The present invention relates to a polymerized antibody labeled with a cyanine dye and a method for preparing the same.
The dye-labeled antibody prepared by labeling an antibody with a dye specifically reacts with an antigen included in a sample solution and is readily recognizable with naked eyes. The dye-labeled antibodies are accordingly applied for immunosensors, each of which takes advantage of an immunological antigen-antibody reaction to detect a target substance included in a sample solution, and are used for diagnoses in a variety of medical institutions.
Cyanine dyes having the high molar absorption coefficient and the high reactivity are often used to label antibodies (Bioconjugate Chemistry Vol. 4, No. 2, pp105-111, 1993).
The functional group of the cyanine dye reacts with and is covalently bound to an amino group or a carboxyl group included in an antibody, and 20 to 50 molecules of the dye are attached to one molecule of the antibody.
The cyanine dye-labeled antibody thus prepared generally has high visual recognizability, and is effectively applied for, for example, immunochromatography to detect a small amount of a specific substance, such as human chorionic gonadotropin (HCG) that is present only in the urine of pregnant women.
One molecule of the antibody generally has only two sites reacting with the antigen and thereby has relatively low reaction sensitivity to the antigen.
When the conventional dye-labeled antigen is used for an immunosensor, the immunosensor accordingly does not have sufficient sensitivity. In the case that the sample solution contains a low concentration of a target substance (antigen), it is difficult to detect the target substance.